CS4299-BQ Datasheet, PDF (13/52 Pages) Cirrus Logic – CrystalClear SoundFusion Audio Codec 97

CS4299-BQ
3. AC LINK FRAME DEFINITION
The AC-link is a bidirectional serial port with data
organized into frames consisting of one 16-bit and
twelve 20-bit time-division multiplexed slots. The
first slot, called the tag slot, contains bits indicating
if the CS4299-BQ is ready to receive data (input
frame) and which, if any, other slots contain valid
data. Slots 1 through 12 contain audio or con-
trol/status data. Both the serial data output and in-
put frames are defined from the controller
perspective, not from the CS4299-BQ perspective.
The controller synchronizes the beginning of a
frame with the assertion of the SYNC signal.
Figure 9 shows the position of each bit location
within the frame. The first bit position in a new se-
rial data frame is F0 and the last bit position in the
serial data frame is F255. When SYNC goes active
(high) and is sampled active by the CS4299-BQ (on
the falling edge of BIT_CLK), both devices are
synchronized to a new serial data frame. The data
on the SDATA_OUT pin at this clock edge is the
final bit of the previous frame’s serial data. On the
next rising edge of BIT_CLK, the first bit of Slot 0
is driven by the controller on the SDATA_OUT
pin. On the next falling edge of BIT_CLK, the
CS4299-BQ latches this data in, as the first bit of
the frame.
Tag Phase
SYNC
BIT_CLK
12.288 MHz
81.4 ns
20.8 µs
(48 kHz)
Data Phase
Bit Frame Position:
SDATA_OUT
F255
0
F0
Valid
Frame
F1
Slot 1
Valid
F2
Slot 2
Valid
F12
F13
Slot 12
Valid
0
F14
Codec
ID1
F15
Codec
ID0
F16
R/W
F35
F36
0 WD15
F56
F57
D19 D18
F76
D19
F96
D19
F255
0
Bit Frame Position:
SDATA_IN
F255
GPIO
INT
F0
Codec
Ready
F1
Slot 1
Valid
F2
Slot 2
Valid
F12
F13
F14 F15
F16
Slot 12
Valid
0
0
0
0
F35
F36
0 RD15
F56 F57
D19 D18
F76
D19
F96
D19
F255
GPIO
INT
Slot 0
Slot 1
Slot 2
Slot 3
Figure 9. AC-link Input and Output Framing
Slot 4
Slots 5-12
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